// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2014 Benoit Steiner <benoit.steiner.goog@gmail.com>
//
// This Source Code Form is subject to the terms of the Mozilla
// Public License v. 2.0. If a copy of the MPL was not distributed
// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.

#ifndef EIGEN_CXX11_TENSOR_TENSOR_DIMENSIONS_H
#define EIGEN_CXX11_TENSOR_TENSOR_DIMENSIONS_H

namespace Eigen {

/** \internal
  *
  * \class TensorDimensions
  * \ingroup CXX11_Tensor_Module
  *
  * \brief Set of classes used to encode and store the dimensions of a Tensor.
  *
  * The Sizes class encodes as part of the type the number of dimensions and the
  * sizes corresponding to each dimension. It uses no storage space since it is
  * entirely known at compile time.
  * The DSizes class is its dynamic sibling: the number of dimensions is known
  * at compile time but the sizes are set during execution.
  *
  * \sa Tensor
  */

// Boilerplate code
namespace internal {

    template <std::ptrdiff_t n, typename Dimension> struct dget
    {
        static const std::ptrdiff_t value = get<n, Dimension>::value;
    };

    template <typename Index, std::ptrdiff_t NumIndices, std::ptrdiff_t n, bool RowMajor> struct fixed_size_tensor_index_linearization_helper
    {
        template <typename Dimensions>
        EIGEN_DEVICE_FUNC static EIGEN_STRONG_INLINE Index run(array<Index, NumIndices> const& indices, const Dimensions& dimensions)
        {
            return array_get < RowMajor ? n - 1 : (NumIndices - n) > (indices) + dget < RowMajor ? n - 1 : (NumIndices - n),
                   Dimensions > ::value * fixed_size_tensor_index_linearization_helper<Index, NumIndices, n - 1, RowMajor>::run(indices, dimensions);
        }
    };

    template <typename Index, std::ptrdiff_t NumIndices, bool RowMajor> struct fixed_size_tensor_index_linearization_helper<Index, NumIndices, 0, RowMajor>
    {
        template <typename Dimensions> EIGEN_DEVICE_FUNC static EIGEN_STRONG_INLINE Index run(array<Index, NumIndices> const&, const Dimensions&) { return 0; }
    };

    template <typename Index, std::ptrdiff_t n> struct fixed_size_tensor_index_extraction_helper
    {
        template <typename Dimensions> EIGEN_DEVICE_FUNC static EIGEN_STRONG_INLINE Index run(const Index index, const Dimensions& dimensions)
        {
            const Index mult = (index == n - 1) ? 1 : 0;
            return array_get<n - 1>(dimensions) * mult + fixed_size_tensor_index_extraction_helper<Index, n - 1>::run(index, dimensions);
        }
    };

    template <typename Index> struct fixed_size_tensor_index_extraction_helper<Index, 0>
    {
        template <typename Dimensions> EIGEN_DEVICE_FUNC static EIGEN_STRONG_INLINE Index run(const Index, const Dimensions&) { return 0; }
    };

}  // end namespace internal

// Fixed size
#ifndef EIGEN_EMULATE_CXX11_META_H
template <typename std::ptrdiff_t... Indices> struct Sizes
{
    typedef internal::numeric_list<std::ptrdiff_t, Indices...> Base;
    const Base t = Base();
    static const std::ptrdiff_t total_size = internal::arg_prod(Indices...);
    static const ptrdiff_t count = Base::count;

    EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE std::ptrdiff_t rank() const { return Base::count; }

    static EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE std::ptrdiff_t TotalSize() { return internal::arg_prod(Indices...); }

    EIGEN_DEVICE_FUNC Sizes() {}
    template <typename DenseIndex> explicit EIGEN_DEVICE_FUNC Sizes(const array<DenseIndex, Base::count>& /*indices*/)
    {
        // todo: add assertion
    }
#if EIGEN_HAS_VARIADIC_TEMPLATES
    template <typename... DenseIndex> EIGEN_DEVICE_FUNC Sizes(DenseIndex...) {}
    explicit EIGEN_DEVICE_FUNC Sizes(std::initializer_list<std::ptrdiff_t> /*l*/)
    {
        // todo: add assertion
    }
#endif

    template <typename T> Sizes& operator=(const T& /*other*/)
    {
        // add assertion failure if the size of other is different
        return *this;
    }

    EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE std::ptrdiff_t operator[](const std::ptrdiff_t index) const
    {
        return internal::fixed_size_tensor_index_extraction_helper<std::ptrdiff_t, Base::count>::run(index, t);
    }

    template <typename DenseIndex> EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE ptrdiff_t IndexOfColMajor(const array<DenseIndex, Base::count>& indices) const
    {
        return internal::fixed_size_tensor_index_linearization_helper<DenseIndex, Base::count, Base::count, false>::run(indices, t);
    }
    template <typename DenseIndex> EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE ptrdiff_t IndexOfRowMajor(const array<DenseIndex, Base::count>& indices) const
    {
        return internal::fixed_size_tensor_index_linearization_helper<DenseIndex, Base::count, Base::count, true>::run(indices, t);
    }
};

namespace internal {
    template <typename std::ptrdiff_t... Indices> EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE std::ptrdiff_t array_prod(const Sizes<Indices...>&)
    {
        return Sizes<Indices...>::total_size;
    }
}  // namespace internal

#else

template <std::ptrdiff_t n> struct non_zero_size
{
    typedef internal::type2val<std::ptrdiff_t, n> type;
};
template <> struct non_zero_size<0>
{
    typedef internal::null_type type;
};

template <std::ptrdiff_t V1 = 0, std::ptrdiff_t V2 = 0, std::ptrdiff_t V3 = 0, std::ptrdiff_t V4 = 0, std::ptrdiff_t V5 = 0> struct Sizes
{
    typedef typename internal::make_type_list<typename non_zero_size<V1>::type,
                                              typename non_zero_size<V2>::type,
                                              typename non_zero_size<V3>::type,
                                              typename non_zero_size<V4>::type,
                                              typename non_zero_size<V5>::type>::type Base;
    static const std::ptrdiff_t count = Base::count;
    static const std::ptrdiff_t total_size = internal::arg_prod<Base>::value;

    EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE ptrdiff_t rank() const { return count; }

    static EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE ptrdiff_t TotalSize() { return internal::arg_prod<Base>::value; }

    Sizes() {}
    template <typename DenseIndex> explicit Sizes(const array<DenseIndex, Base::count>& /*indices*/)
    {
        // todo: add assertion
    }
    template <typename T> Sizes& operator=(const T& /*other*/)
    {
        // add assertion failure if the size of other is different
        return *this;
    }

#if EIGEN_HAS_VARIADIC_TEMPLATES
    template <typename... DenseIndex> Sizes(DenseIndex... /*indices*/) {}
    explicit Sizes(std::initializer_list<std::ptrdiff_t>)
    {
        // todo: add assertion
    }
#else
    EIGEN_DEVICE_FUNC explicit Sizes(const DenseIndex) {}
    EIGEN_DEVICE_FUNC Sizes(const DenseIndex, const DenseIndex) {}
    EIGEN_DEVICE_FUNC Sizes(const DenseIndex, const DenseIndex, const DenseIndex) {}
    EIGEN_DEVICE_FUNC Sizes(const DenseIndex, const DenseIndex, const DenseIndex, const DenseIndex) {}
    EIGEN_DEVICE_FUNC Sizes(const DenseIndex, const DenseIndex, const DenseIndex, const DenseIndex, const DenseIndex) {}
#endif

    EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE Index operator[](const Index index) const
    {
        switch (index)
        {
        case 0:
            return internal::get<0, Base>::value;
        case 1:
            return internal::get<1, Base>::value;
        case 2:
            return internal::get<2, Base>::value;
        case 3:
            return internal::get<3, Base>::value;
        case 4:
            return internal::get<4, Base>::value;
        default:
            eigen_assert(false && "index overflow");
            return static_cast<Index>(-1);
        }
    }

    template <typename DenseIndex> EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE ptrdiff_t IndexOfColMajor(const array<DenseIndex, Base::count>& indices) const
    {
        return internal::fixed_size_tensor_index_linearization_helper<DenseIndex, Base::count, Base::count, false>::run(indices,
                                                                                                                        *reinterpret_cast<const Base*>(this));
    }
    template <typename DenseIndex> EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE ptrdiff_t IndexOfRowMajor(const array<DenseIndex, Base::count>& indices) const
    {
        return internal::fixed_size_tensor_index_linearization_helper<DenseIndex, Base::count, Base::count, true>::run(indices,
                                                                                                                       *reinterpret_cast<const Base*>(this));
    }
};

namespace internal {
    template <std::ptrdiff_t V1, std::ptrdiff_t V2, std::ptrdiff_t V3, std::ptrdiff_t V4, std::ptrdiff_t V5>
    EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE std::ptrdiff_t array_prod(const Sizes<V1, V2, V3, V4, V5>&)
    {
        return Sizes<V1, V2, V3, V4, V5>::total_size;
    }
}  // namespace internal

#endif

// Boilerplate
namespace internal {
    template <typename Index, std::ptrdiff_t NumIndices, std::ptrdiff_t n, bool RowMajor> struct tensor_index_linearization_helper
    {
        static EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE Index run(array<Index, NumIndices> const& indices, array<Index, NumIndices> const& dimensions)
        {
            return array_get < RowMajor ?
                       n :
                       (NumIndices - n - 1) > (indices) + array_get < RowMajor ?
                       n :
                       (NumIndices - n - 1) > (dimensions)*tensor_index_linearization_helper<Index, NumIndices, n - 1, RowMajor>::run(indices, dimensions);
        }
    };

    template <typename Index, std::ptrdiff_t NumIndices, bool RowMajor> struct tensor_index_linearization_helper<Index, NumIndices, 0, RowMajor>
    {
        static EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE Index run(array<Index, NumIndices> const& indices, array<Index, NumIndices> const&)
        {
            return array_get < RowMajor ? 0 : NumIndices - 1 > (indices);
        }
    };
}  // end namespace internal

// Dynamic size
template <typename DenseIndex, int NumDims> struct DSizes : array<DenseIndex, NumDims>
{
    typedef array<DenseIndex, NumDims> Base;
    static const int count = NumDims;

    EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE Index rank() const { return NumDims; }

    EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE DenseIndex TotalSize() const { return (NumDims == 0) ? 1 : internal::array_prod(*static_cast<const Base*>(this)); }

    EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE DSizes()
    {
        for (int i = 0; i < NumDims; ++i) { (*this)[i] = 0; }
    }
    EIGEN_DEVICE_FUNC explicit DSizes(const array<DenseIndex, NumDims>& a) : Base(a) {}

    EIGEN_DEVICE_FUNC explicit DSizes(const DenseIndex i0)
    {
        eigen_assert(NumDims == 1);
        (*this)[0] = i0;
    }

    EIGEN_DEVICE_FUNC DSizes(const DimensionList<DenseIndex, NumDims>& a)
    {
        for (int i = 0; i < NumDims; ++i) { (*this)[i] = a[i]; }
    }

    // Enable DSizes index type promotion only if we are promoting to the
    // larger type, e.g. allow to promote dimensions of type int to long.
    template <typename OtherIndex>
    EIGEN_DEVICE_FUNC explicit DSizes(
        const array<OtherIndex, NumDims>& other,
        // Default template parameters require c++11.
        typename internal::enable_if<internal::is_same<DenseIndex, typename internal::promote_index_type<DenseIndex, OtherIndex>::type>::value, void*>::type =
            0)
    {
        for (int i = 0; i < NumDims; ++i) { (*this)[i] = static_cast<DenseIndex>(other[i]); }
    }

#ifdef EIGEN_HAS_INDEX_LIST
    template <typename FirstType, typename... OtherTypes> EIGEN_DEVICE_FUNC explicit DSizes(const Eigen::IndexList<FirstType, OtherTypes...>& dimensions)
    {
        for (int i = 0; i < dimensions.count; ++i) { (*this)[i] = dimensions[i]; }
    }
#endif

#ifndef EIGEN_EMULATE_CXX11_META_H
    template <typename std::ptrdiff_t... Indices> EIGEN_DEVICE_FUNC DSizes(const Sizes<Indices...>& a)
    {
        for (int i = 0; i < NumDims; ++i) { (*this)[i] = a[i]; }
    }
#else
    template <std::ptrdiff_t V1, std::ptrdiff_t V2, std::ptrdiff_t V3, std::ptrdiff_t V4, std::ptrdiff_t V5>
    EIGEN_DEVICE_FUNC DSizes(const Sizes<V1, V2, V3, V4, V5>& a)
    {
        for (int i = 0; i < NumDims; ++i) { (*this)[i] = a[i]; }
    }
#endif

#if EIGEN_HAS_VARIADIC_TEMPLATES
    template <typename... IndexTypes>
    EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE explicit DSizes(DenseIndex firstDimension, DenseIndex secondDimension, IndexTypes... otherDimensions)
        : Base(
              {{ firstDimension,
                 secondDimension,
                 otherDimensions... }})
    {
        EIGEN_STATIC_ASSERT(sizeof...(otherDimensions) + 2 == NumDims, YOU_MADE_A_PROGRAMMING_MISTAKE)
    }
#else
    EIGEN_DEVICE_FUNC DSizes(const DenseIndex i0, const DenseIndex i1)
    {
        eigen_assert(NumDims == 2);
        (*this)[0] = i0;
        (*this)[1] = i1;
    }
    EIGEN_DEVICE_FUNC DSizes(const DenseIndex i0, const DenseIndex i1, const DenseIndex i2)
    {
        eigen_assert(NumDims == 3);
        (*this)[0] = i0;
        (*this)[1] = i1;
        (*this)[2] = i2;
    }
    EIGEN_DEVICE_FUNC DSizes(const DenseIndex i0, const DenseIndex i1, const DenseIndex i2, const DenseIndex i3)
    {
        eigen_assert(NumDims == 4);
        (*this)[0] = i0;
        (*this)[1] = i1;
        (*this)[2] = i2;
        (*this)[3] = i3;
    }
    EIGEN_DEVICE_FUNC DSizes(const DenseIndex i0, const DenseIndex i1, const DenseIndex i2, const DenseIndex i3, const DenseIndex i4)
    {
        eigen_assert(NumDims == 5);
        (*this)[0] = i0;
        (*this)[1] = i1;
        (*this)[2] = i2;
        (*this)[3] = i3;
        (*this)[4] = i4;
    }
#endif

    EIGEN_DEVICE_FUNC DSizes& operator=(const array<DenseIndex, NumDims>& other)
    {
        *static_cast<Base*>(this) = other;
        return *this;
    }

    // A constexpr would be so much better here
    EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE DenseIndex IndexOfColMajor(const array<DenseIndex, NumDims>& indices) const
    {
        return internal::tensor_index_linearization_helper<DenseIndex, NumDims, NumDims - 1, false>::run(indices, *static_cast<const Base*>(this));
    }
    EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE DenseIndex IndexOfRowMajor(const array<DenseIndex, NumDims>& indices) const
    {
        return internal::tensor_index_linearization_helper<DenseIndex, NumDims, NumDims - 1, true>::run(indices, *static_cast<const Base*>(this));
    }
};

template <typename IndexType, int NumDims> std::ostream& operator<<(std::ostream& os, const DSizes<IndexType, NumDims>& dims)
{
    os << "[";
    for (int i = 0; i < NumDims; ++i)
    {
        if (i > 0)
            os << ", ";
        os << dims[i];
    }
    os << "]";
    return os;
}

// Boilerplate
namespace internal {
    template <typename Index, std::ptrdiff_t NumIndices, std::ptrdiff_t n, bool RowMajor> struct tensor_vsize_index_linearization_helper
    {
        static EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE Index run(array<Index, NumIndices> const& indices, std::vector<DenseIndex> const& dimensions)
        {
            return array_get < RowMajor ?
                       n :
                       (NumIndices - n - 1) > (indices) + array_get < RowMajor ?
                       n :
                       (NumIndices - n - 1) >
                               (dimensions)*tensor_vsize_index_linearization_helper<Index, NumIndices, n - 1, RowMajor>::run(indices, dimensions);
        }
    };

    template <typename Index, std::ptrdiff_t NumIndices, bool RowMajor> struct tensor_vsize_index_linearization_helper<Index, NumIndices, 0, RowMajor>
    {
        static EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE Index run(array<Index, NumIndices> const& indices, std::vector<DenseIndex> const&)
        {
            return array_get < RowMajor ? 0 : NumIndices - 1 > (indices);
        }
    };
}  // end namespace internal

namespace internal {

    template <typename DenseIndex, int NumDims> struct array_size<const DSizes<DenseIndex, NumDims>>
    {
        static const ptrdiff_t value = NumDims;
    };
    template <typename DenseIndex, int NumDims> struct array_size<DSizes<DenseIndex, NumDims>>
    {
        static const ptrdiff_t value = NumDims;
    };
#ifndef EIGEN_EMULATE_CXX11_META_H
    template <typename std::ptrdiff_t... Indices> struct array_size<const Sizes<Indices...>>
    {
        static const std::ptrdiff_t value = Sizes<Indices...>::count;
    };
    template <typename std::ptrdiff_t... Indices> struct array_size<Sizes<Indices...>>
    {
        static const std::ptrdiff_t value = Sizes<Indices...>::count;
    };
    template <std::ptrdiff_t n, typename std::ptrdiff_t... Indices> EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE std::ptrdiff_t array_get(const Sizes<Indices...>&)
    {
        return get<n, internal::numeric_list<std::ptrdiff_t, Indices...>>::value;
    }
    template <std::ptrdiff_t n> EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE std::ptrdiff_t array_get(const Sizes<>&)
    {
        eigen_assert(false && "should never be called");
        return -1;
    }
#else
    template <std::ptrdiff_t V1, std::ptrdiff_t V2, std::ptrdiff_t V3, std::ptrdiff_t V4, std::ptrdiff_t V5> struct array_size<const Sizes<V1, V2, V3, V4, V5>>
    {
        static const ptrdiff_t value = Sizes<V1, V2, V3, V4, V5>::count;
    };
    template <std::ptrdiff_t V1, std::ptrdiff_t V2, std::ptrdiff_t V3, std::ptrdiff_t V4, std::ptrdiff_t V5> struct array_size<Sizes<V1, V2, V3, V4, V5>>
    {
        static const ptrdiff_t value = Sizes<V1, V2, V3, V4, V5>::count;
    };
    template <std::ptrdiff_t n, std::ptrdiff_t V1, std::ptrdiff_t V2, std::ptrdiff_t V3, std::ptrdiff_t V4, std::ptrdiff_t V5>
    EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE std::ptrdiff_t array_get(const Sizes<V1, V2, V3, V4, V5>&)
    {
        return get<n, typename Sizes<V1, V2, V3, V4, V5>::Base>::value;
    }

#endif

    template <typename Dims1, typename Dims2, ptrdiff_t n, ptrdiff_t m> struct sizes_match_below_dim
    {
        static EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE bool run(Dims1&, Dims2&) { return false; }
    };
    template <typename Dims1, typename Dims2, ptrdiff_t n> struct sizes_match_below_dim<Dims1, Dims2, n, n>
    {
        static EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE bool run(Dims1& dims1, Dims2& dims2)
        {
            return (array_get<n - 1>(dims1) == array_get<n - 1>(dims2)) && sizes_match_below_dim<Dims1, Dims2, n - 1, n - 1>::run(dims1, dims2);
        }
    };
    template <typename Dims1, typename Dims2> struct sizes_match_below_dim<Dims1, Dims2, 0, 0>
    {
        static EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE bool run(Dims1&, Dims2&) { return true; }
    };

}  // end namespace internal

template <typename Dims1, typename Dims2> EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE bool dimensions_match(Dims1 dims1, Dims2 dims2)
{
    return internal::sizes_match_below_dim<Dims1, Dims2, internal::array_size<Dims1>::value, internal::array_size<Dims2>::value>::run(dims1, dims2);
}

}  // end namespace Eigen

#endif  // EIGEN_CXX11_TENSOR_TENSOR_DIMENSIONS_H
